The invention relates to the use of the indolocarbazole compound K-252a, or a preferred derivative thereof, to treat a pathological condition of the prostate gland.
Disorders of the prostate gland are common in aging men. For example, prostatic hyperplasia affects 90% of men by the age of 80 years. Where the hyperplastic condition causes urinary obstruction, it is alleviated by surgical techniques. Prostate cancer, which is now the most frequently diagnosed cancer in men, is most frequently treated by surgery, by radiation therapy, or by androgen deprivation, e.g., by castration, by estrogen therapy, by administration of analogues of adrenocorticotropic hormone (ACTH) (Harrison's Principles of Internal Medicine, 12th ed. Wilson et al. eds. McGraw-Hill, N.Y. pgs. 1629-32), or by administration of Suramin, a non-specific and highly toxic growth factor inhibitor.
The neurotrophin family of growth factors includes nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin 4/5 (NT-4/5). These basic proteins are approximately 120 amino acids in length, share .apprxeq.50% sequence homology, and are highly conserved among mammalian species (Issackson et al., FEBS Lett. 285:260-64, 1991). NGF was the first growth factor discovered and remains the best characterized neurotrophin. NGF is required for normal development of sensory and sympathetic neurons and for normal function of these cells in adult life (Levi-Montalcini, Annu. Rev. Neurosci. 5:341-362, 1982; Yankner et al., Annu. Rev. Biochem 59:845-868, 1982).
Neurotrophin binding and activation of a set of high affinity receptors (trks) is necessary and sufficient to mediate most of the biological effects of the neurotrophins. The trks are transmembrane proteins which contain an extracellular ligand binding domain, a transmembrane sequence, and a cytoplasmic tyrosine kinase domain. The trks comprise a family of structurally related proteins with preferential binding specificities for the individual neurotrophins. TrkA, which is sometimes referred to as trk, is a high-affinity receptor for NGF, but it can also mediate biological responses to NT-3 under particular conditions (Kaplan et al. Science 252:554-558, 1991; Klein et al., Cell 65:189-197, 1991; Cordon-Cardo et al., Cell 66:173-183, 1991). TrkB binds and mediates functions of BDNF, NT-3, and NT4/5 (Klein et al. Cell 66:395-403, 1991; Squinto et al., Cell 65:885-893, 1991; Klein et al. Neuron 8:947-956, 1992). TrkC is relatively specific for NT-3 (Lamballe et al., Cell 66:967-979, 1991).
K-252a, an alkaloid-like material isolated from the culture broth of Nocardiosis sp. and Actinomadula sp. is an inhibitor of protein kinase C, A, and G, as well as myosin light-chain kinase and phosphorylase kinase.